Automotive fog lamps are auxiliary forward lighting devices mounted low in the front fascia of an automobile. Fog lamps direct light low and toward the ground to provide improved visibility during poor weather conditions. The automobile industry has defined a standard opening in the front fascia for fog lamps that is circular in shape and approximately two inches in diameter. Such opening is the smallest standard front fascia opening for forward lighting.
Traditional “projector” automotive fog lamps include a halogen light bulb surrounded by a polyellipsoidal reflector, which is covered by a glass aspheric condensing lens. Such projector fog lamps usually include a shade obstructing a large portion of the light path out of the lamp, in order to create a top cutoff in the produced light pattern and thereby reduce glare. In operation, traditional halogen fog lamps typically consume about 55 watts of electrical power. Traditional halogen fog lamps typically have optical efficiency of about 18 percent.
Light-emitting diode (LED) light sources provide an efficient light source. LEDs for automotive applications typically consume about 12 watts of electrical power in operation. LEDs also generally have much longer expected lifetimes than halogen light bulbs. However, LEDs differ from halogen light bulbs in several characteristics. LEDs typically produce lower amounts of luminous flux. Additionally, the longevity and light production of LEDs are both sensitive to operating temperature, requiring thermal management.